Tricky weather conditions at Veeplaas Reservoir during the building of the roof structure led to damage that had to be repaired quickly and efficiently. Coega Development Corporation contracted MCS to repair the concrete structure, and the product of choice for the job was Sika, their preferred supplier of innovative construction products.

While the roof was being constructed, the contractor had lost control of the finishing of his concrete due to extremely high temperatures and wind speeds, which dried the concrete surface quickly. MCS was contracted to correct the roof structure, and to waterproof the internal joints of the reservoir to prevent the unit from leaking.

The state-of-the-art Sika products used include SikaTop Armatec 110 EC (20 x 1,75lt kits), which was used as a bonding agent for the repair mortar, Sika MonoTop-612. SikaTop Armatec 110 EC is a cement-based, epoxy-modified, anti-corrosion coating and bonding agent for use on concrete, mortar or steel and as a protective coating for reinforcement steel embedded in concrete to prevent corrosion. It contains corrosion inhibitors, offers excellent adhesion to steel and concrete, and acts as a barrier against penetration of water and chlorides. Sika MonoTop-612 (85 x 25kg bags), a cementitious, polymer-modified high strength repair mortar containing silica fume and synthetic reinforcement fibres, was used in concrete repairs to the roof structure. MonoTop-612 is a sprayable or hand-placed concrete repair and reprofiling system; it offers excellent workability characteristics, adjustable consistency, excellent slump resistance and is suitable for application onto overhead and vertical surfaces.

The Sikadur-Combiflex System (965m), a high performance joint sealing system consisting of a flexible Hypalon waterproofing tape and Combiflex epoxy adhesive, was applied to the internal joints. The Sikadur-Combiflex System is employed primarily in the construction of water retaining structures such as this reservoir; and as a highly specialised waterproofing system, it is used for expansion and connection joints as well as for cracks, allowing irregular and high movement in more than one direction, whilst maintaining a high quality seal.

Sikadur-31 CF Normal (60 x 7,5lt kits), a solvent-free, moisture tolerant, thixotropic, structural two-part adhesive and repair mortar based on a combination of epoxy resins and special fillers, was applied as an adhesive for the Sikadur Combiflex system. Suitable for dry and damp concrete surfaces, Sikadur-31 CF Normal is designed for use at temperatures between +10°C and +30°C, and provides good adhesion to most construction materials. At times during the repair work the temperatures in the reservoir rose as high as 45°C as the roof slab was already in place, while only two manholes were open to allow entry to the reservoir. The extreme heat reduced the pot life of the Sikadur-31CF Normal epoxy, which meant that smaller quantities had to be mixed. The contractor also had to speed up the application process by additional on-site labour reinforcements.

Despite the enormous challenges faced by the team, the repair work was completed quickly and successfully. Coega Development Corporation can be confident that the Veeplaas Reservoir concrete roof structure was completed to Sika’s stringent, world-class standards - ensuring the highest quality roofing that is built to last.